1. Field of the Invention
The present invention relates generally to fuel systems, and more particularly to apparatus for treating and conditioning fuel for use in an internal combustion engine.
2. Background Art
It has been recognized for many years that the addition of small amounts of certain metallic elements, such as tin, can improve the combustion characteristics of liquid fuels such as petrol and diesel oil. It is also well known that there are increasingly strict regulations with regard to exhaust emissions from internal combustion engines due to the harmful effects of certain exhaust gases on the environment. The improvement in the combustion characteristics which is effected by the addition of trace amounts of metals to the fuel can therefore help with emission control by reducing the pollution effects of exhaust gases by reducing the amount of unburnt fuel exhausted, as well as by improving engine efficiency by increasing the amount or percentage of the fuel actually burnt in the engine.
Furthermore, it has been prior practice to add relatively large amounts of certain metals, notably lead, to liquid fuels, primarily to suppress preignition and eliminate engine "knock". Recently, the use of these additives (primarily tetraethyl lead) has been largely terminated due to environmental concerns, and alternative formulations have been employed to minimize preignition. However, these metal additives also had the secondary purpose of protecting and enhancing the condition of certain internal components of the engines, notably valve seats; while most newer engines are designed to operate on lead-free fuels, many of the older-type engines will remain in service for many years to come, and these will be subject to potential damage (e.g., valve seat erosion) because leaded fuels will no longer be available. However, it is believed that engine protection can be enhanced, and much of this wear or damage reduced or eliminated, by adding trace amounts of certain metals to the fuel, and it is also believed that suitable amounts may be provided for this without posing environmental concerns, being that it is no longer necessary to include amounts sufficient to suppress preignition. Furthermore, it is believed to be possible for this purpose to use trace amounts of certain metals which do not pose the same threat to the environment as prior materials.
Accordingly, it is an object of the present invention to provide an apparatus for conditioning liquid fuel prior to delivery to an internal combustion engine by adding a trace level of a metallic element or elements to the fuel.